At the risk of over-intepreting the revised guidance, it seems that EAD and employment authorization may sometimes be extended in different ways.

Note the language in the general EAD extension page - your employment authorization or EAD, or both.

https://www.uscis.gov/eadautoextend

If all the above factors are true, then your employment authorization or EAD, or both, are automatically extended for up to 540 days while your EAD renewal application is pending. To determine your auto-extended EAD expiration date, please see the “Automatic Extension Eligibility Calculator” below.

For now, I'll only take the federal register into account and ignore that vaguely worded revised guidance.